Regarding a sensor system in which data measured by sensors installed in a plurality of devices is collected, the known examples include an IoT solution for monitoring the flooding of rivers and sewers and an IoT solution for detecting defects in roads and bridges. In a sensor system, there are times when the data in the devices, such as measurement data obtained at the same timing in a plurality of devices, is collected via gateways (GWs) installed near the devices. In that case, in the GWs, as a result of collecting the measurement data obtained at the same timing, there occurs overlapping of notification timings of a plurality of devices thereby causing interference or retransmission of the measurement data from the devices.
In a sensor system, when there is overlapping of the notification timings for notifying the measurement data from a plurality of devices to GWs, the notification timings are time-shared in communication slots of predetermined time intervals, and the notification timing for notifying the measurement data of each device is assigned to one communication slot. With that, data interference or data retransmission between the GWs and the devices is avoided. Besides, in a sensor system, priority is assigned to the devices, and the notification timing of each device is varied according to the priority of that device.
[Patent Literature 1] Japanese Patent No. 5641381
[Patent Literature 2] Japanese Laid-open Patent Publication No. 2014-209311
[Patent Literature 3] International Publication Pamphlet No. 2012/056551
[Patent Literature 4] Japanese Laid-open Patent Publication No. 2012-195705
In a sensor system, when there is overlapping of the notification timings for notifying the measurement data from a plurality of devices to GWs, the notification timing of each device is varied according to the priority of that device. However, in a sensor system, if there is a plurality of devices having the same priority, then it is difficult for the notification timing of each device to be varied, and it is difficult for data interference or data retransmission to be avoided. That results in data loss and data delay.